Init with existing index in non-default location not working

[LarsAC]

Hello,

I am getting an error trying to init RAGatouille from an existing index at /mnt/index (within a docker container). There is an error message:

The relevant part of my code is

        RAG = RAGPretrainedModel.from_index(f"/mnt/index/.ragatouille/colbert/indexes/{INDEX_NAME}/")
        retriever = RAG.as_langchain_retriever(index_name=INDEX_NAME)

which runs ok, the error below occurs when my langchain chain is invoked.

Here is the log:

Loading searcher for index grt_ragatouille_colbertv20 for the first time... This may take a few seconds
2024-01-13 22:21:19 - [Errno 2] No such file or directory: '.ragatouille/colbert/indexes/grt_ragatouille_colbertv20/plan.json'
Traceback (most recent call last):
  File "/usr/local/lib/python3.11/site-packages/colbert/infra/config/base_config.py", line 94, in load_from_index
    loaded_config, _ = cls.from_path(metadata_path)
                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/site-packages/colbert/infra/config/base_config.py", line 44, in from_path
    with open(name) as f:
         ^^^^^^^^^^
FileNotFoundError: [Errno 2] No such file or directory: '.ragatouille/colbert/indexes/grt_ragatouille_colbertv20/metadata.json'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/local/lib/python3.11/site-packages/chainlit/utils.py", line 39, in wrapper
    return await user_function(**params_values)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/app/app.py", line 143, in main
    res = await chain.acall(message.content, callbacks=[cb])
          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/site-packages/langchain/chains/base.py", line 413, in acall
    return await self.ainvoke(
           ^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/site-packages/langchain/chains/base.py", line 209, in ainvoke
    raise e
  File "/usr/local/lib/python3.11/site-packages/langchain/chains/base.py", line 203, in ainvoke
    await self._acall(inputs, run_manager=run_manager)
  File "/usr/local/lib/python3.11/site-packages/langchain/chains/conversational_retrieval/base.py", line 207, in _acall
    docs = await self._aget_docs(new_question, inputs, run_manager=_run_manager)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/site-packages/langchain/chains/conversational_retrieval/base.py", line 330, in _aget_docs
    docs = await self.retriever.aget_relevant_documents(
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/site-packages/langchain_core/retrievers.py", line 281, in aget_relevant_documents
    raise e
  File "/usr/local/lib/python3.11/site-packages/langchain_core/retrievers.py", line 274, in aget_relevant_documents
    result = await self._aget_relevant_documents(
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/site-packages/langchain_core/retrievers.py", line 166, in _aget_relevant_documents
    return await run_in_executor(
           ^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/site-packages/langchain_core/runnables/config.py", line 490, in run_in_executor
    return await asyncio.get_running_loop().run_in_executor(
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/asyncio/futures.py", line 287, in __await__
    yield self  # This tells Task to wait for completion.
    ^^^^^^^^^^
  File "/usr/local/lib/python3.11/asyncio/tasks.py", line 339, in __wakeup
    future.result()
  File "/usr/local/lib/python3.11/asyncio/futures.py", line 203, in result
    raise self._exception.with_traceback(self._exception_tb)
  File "/usr/local/lib/python3.11/concurrent/futures/thread.py", line 58, in run
    result = self.fn(*self.args, **self.kwargs)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/site-packages/ragatouille/RAGPretrainedModel.py", line 206, in _get_relevant_documents
    docs = self.model.search(query, **self.kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/site-packages/ragatouille/RAGPretrainedModel.py", line 184, in search
    return self.model.search(
           ^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/site-packages/ragatouille/models/colbert.py", line 240, in search
    self._load_searcher(index_name=index_name, force_fast=force_fast)
  File "/usr/local/lib/python3.11/site-packages/ragatouille/models/colbert.py", line 204, in _load_searcher
    self.searcher = Searcher(
                    ^^^^^^^^^
  File "/usr/local/lib/python3.11/site-packages/colbert/searcher.py", line 33, in __init__
    self.index_config = ColBERTConfig.load_from_index(self.index)
                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/site-packages/colbert/infra/config/base_config.py", line 97, in load_from_index
    loaded_config, _ = cls.from_path(metadata_path)
                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/site-packages/colbert/infra/config/base_config.py", line 44, in from_path
    with open(name) as f:
         ^^^^^^^^^^
FileNotFoundError: [Errno 2] No such file or directory: '.ragatouille/colbert/indexes/grt_ragatouille_colbertv20/plan.json'```

Looks like `_load_searcher` in `colbert.py` does not pass an `index_root` and also no `config` when creating a `Searcher` but this was just a very quick assessment in the code.

[bclavie]

Hey Lars! Nice catch, I think know exactly how this got introduced -- as a workaround for an issue in loading configs for Searcher upstream, we let it fetch the config from the checkpoint without overrides, but it means that it defaults to the generation-time "root"!

I've pushed a workaround in #45, should be good to go!

(Also, to convert to langchain, simply doing:

RAG = RAGPretrainedModel.from_index(f"/mnt/index/.ragatouille/colbert/indexes/{INDEX_NAME}/")
retriever = RAG.as_langchain_retriever()

should be enough, passing the index name again isn't needed as the main RAG object has already initiated itself against the index)

[LarsAC]

Thanks for confirmation and quick resolution - confirmed working.